Dosimeters according to the invention can be used to replace either the current active sampling charcoal tube monitors, which need to be worn with sampling pumps and utilize solvent extraction for analysis, or the badge-type passive dosimeters, which require a solvent extraction procedure for sample analysis. The use of a sampling pump reduces a worker's mobility whereas the use of solvent extraction increases analysis time and exposes laboratory personnel to hazardous chemicals. The elimination of sampling pumps and solvent extraction techniques greatly simplifies the sample collection and analysis of ambient air aromatics for personal exposure monitoring. The analytical procedure is fully automated.
Assignee's current NIOSH Method 1501 for aromatic hydrocarbon sampling uses a charcoal packed glass tube as a sample collection trap. A small personal pump is connected to this charcoal tube and a known volume of air is drawn through the tube during sampling. The tube is then extracted with carbon disulfide (1 mL). A fraction of the extract (1-2 .mu.L) is then injected into a gas chromatograph (GC) for analysis. Alternatively, a passive badge-type 3M 3500 Organic Vapor Monitor (OVM) can be used for BTEX sampling. This latter method eliminates the use of personal sampling pumps, but it still requires the use of a CS.sub.2 extraction procedure.
There are several reports and articles in the literature on passive dosimeters of various designs. Some reported the use of Perkin-Elmer tube-type passive dosimeters with sorbent material sold under the trademark TENAX. However, all reported studies use a large amount of packing material to fill the dosimeter tube (.about.200 mg). None use a wafer type configuration of sorbent packing design. The large amount of packing tends to give a large background signal when analyzed by thermal desorption which decreases the detection limit of the method.
Applicants also acknowledge their use of a charcoal absorbent wafer in a Perkin-Elmer ATD-50 automatic thermal desorption system for detection of 1,3-butadiene. The wafer was cut from the charcoal disk taken from a 3M 3500 organic vapor monitor. Charcoal is used only for extremely volatile components and is not suitable for BTEX determination using thermal desorption methods. Also, the charcoal wafer has structural integrity and did not require wire gauze structural elements. This was reported as Abstract No. 129 in the Salt Palace Center Abstract Book, May 1814 24, 1991.
The article by MacLeod G., and Ames, J. M., entitled "Comparative Assessment Of The Artifact Background On Thermal Desorption Of TENAX GC And TENAX TA" which appeared in the Journal of Chromatography, 355-398 (1986) discussed the use of passive dosimeter tubes with 200 mg TENAX sorbent material packing. The non-wafer design passive dosimeter reported in this article requires repeated special high temperature and long duration thermal cleaning to reduce the GC analysis background. An article by Fields, B., entitled "Diffusive Sampling Onto Solid Adsorbents For The Analysis Of Benzene And 1,3-Butadiene In Air By Gas Chromatography" appeared in Diffusive Sampling-An Alternative Approach to Workplace Air Monitoring, A. Berlin, R. H. Brown, K. J. Saunders, Eds., Royal Society Chemistry, London (1987) pp. 85 and reported the use of Perkin-Elmer tube-type passive dosimeters packed with sorbent material sold under the trademark POROPAK Q, for personal monitoring. The article by Yin, C. C. and Layton-Matthews, G., entitled "Development Of A Passive Sampler For Monitoring Ambient Levels Of Organic Vapours Particularly Benzene" also appearing in Diffusive Sampling-An Alternative Approach To Workplace Air Monitoring, A. Berlin, R. H. Brown, K. J. Saunders, Eds., Royal Society Chemistry, London (1987) pp. 78 reported a large diffusive surface area passive dosimeter with 200 mg of TENAX sorbent material packing for benzene monitoring. The article by De Bortoli, M., Knoppel, H., Pecchio, E. and Vissers, H., entitled "Performance Of A Thermally Desorbable Diffusion Sampler For Personal And Indoor Air Monitoring" appeared in Environment International, Vol. 15, pp 427-434, 1989 and reported the use of a 160 mm long glass tube filled with 25-100 mm length of sorbent material for personal and indoor air monitoring.